M34E02-F datasheet(9/36 Pages) STMICROELECTRONICS

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M34E02-F

Signal description

2.4

Write Control (WC)

This input signal is provided for protecting the contents of the whole memory from

inadvertent write operations. Write Control (WC) is used to enable (when driven low) or

disable (when driven high) write instructions to the entire memory area or to the Protection

When Write Control (WC) is tied low or left unconnected, the write protection of the first half

of the memory is determined by the status of the Protection Register.

2.5

Supply voltage (VCC)

2.5.1

Operating supply voltage (VCC)

Prior to selecting the memory and issuing instructions to it, a valid and stable VCC voltage

within the specified [VCC(min), VCC(max)] range must be applied (see Table 8). In order to

secure a stable DC supply voltage, it is recommended to decouple the VCC line with a

suitable capacitor (usually of the order of 10 nF to 100 nF) close to the VCC/VSS package

pins.

This voltage must remain stable and valid until the end of the transmission of the instruction

and, for a Write instruction, until the completion of the internal write cycle (tW).

2.5.2

Power-up conditions

The VCC voltage has to rise continuously from 0 V up to the minimum VCC operating voltage

defined in Table 8 and the rise time must not vary faster than 1 V/µs.

2.5.3

Device reset

In order to prevent inadvertent write operations during power-up, a power-on reset (POR)

circuit is included. At power-up, the device does not respond to any instruction until VCC

reaches the internal reset threshold voltage (this threshold is lower than the minimum VCC

operating voltage defined in Table 8).

When VCC passes over the POR threshold, the device is reset and enters the Standby

Power mode. However, the device must not be accessed until VCC reaches a valid and

stable VCC voltage within the specified [VCC(min), VCC(max)] range.

In a similar way, during power-down (continuous decrease in VCC), as soon as VCC drops

below the power-on reset threshold voltage, the device stops responding to any instruction

sent to it.

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